256 HARRIS: RELATIONSHIP OF OVULES TO SEEDS 
this table is that in all three series 7,, is negative and of a very 
low order, but quite possibly significant even in the Ohio series. 
E. Summary and Discussion 
The foregoing pages embody the results of an attempt to 
ascertain the relationship between the number of ovules per pod 
and the capacity of the pod for maturing its ovules into seeds in 
the leguminous plant Cercis canadensis. The methods of analysis 
are those of an earlier paper on Phaseolus. The data in hand 
lead to the following conclusions: 
The correlations for number of ovules formed and number of 
seeds developing per pod, os, have always been found positive and 
of a moderate, considerable or even high intensity. 
Regression of number of seeds on number of ovules per pod is 
sensibly linear in a population of pods from many individual trees. 
Possibly, however, there is a departure from linearity in the pods 
with eight ovules; in my largest series there are only 36 of these 
pods out of a total of 28,554, and this number is too small to be 
given great importance. 
The significance of the linearity of regression is two-fold. 
Statistically, it justifies describing the interdependence between 
the number of ovules formed and the number of seeds maturing 
by the coefficient of correlation. Biologically, it shows that the 
rate of increase in number of seeds developing per pod remains 
the same as we pass from pods with the lowest to pods with the 
highest numbers of ovules. 
Wherever large series of pod have been examined, the corre- 
lation between the number of ovules per pod and the capacity of 
the pods for maturing their seeds, 7,., has a negative sign and a 
low, usually a very low, magnitude. For every large series ex- 
amined the value of r,, has been over 2.5 times its probable error. 
These evidences can leave little doubt of the existence of a slight 
negative relationship between the number of ovules formed and 
the capacity of the pod for maturing its ovules into seeds, the pods 
with the larger number of ovules producing relatively fewer seeds. 
In a subsequent paper, these conclusions will be tested upon 
the more homogeneous collections of pods from individual trees. 
Until then further discussion may be reserved. 
CoLp Sprinc Harsor, New York 
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